An in-line photonic biosensor for monitoring of glucose concentrations.

Ala'Aldeen Al-Halhouli,Stefanie Demming,Stephanus Büttgenbach,Laila Alahmad,Andreu Liobera

doi:10.3390/s140915749

Abstract

This paper presents two PDMS photonic biosensor designs that can be used for continuous monitoring of glucose concentrations. The first design, the internally immobilized sensor, consists of a reactor chamber, micro-lenses and self-alignment structures for fiber optics positioning. This sensor design allows optical detection of glucose concentrations under continuous glucose flow conditions of 33 μL/h based on internal co-immobilization of glucose oxidase (GOX) and horseradish peroxidase (HRP) on the internal PDMS surface of the reactor chamber. For this design, two co-immobilization methods, the simple adsorption and the covalent binding (PEG) methods were tested. Experiments showed successful results when using the covalent binding (PEG) method, where glucose concentrations up to 5 mM with a coefficient of determination (R2) of 0.99 and a limit of detection of 0.26 mM are detectable. The second design is a modified version of the internally immobilized sensor, where a microbead chamber and a beads filling channel are integrated into the sensor. This modification enabled external co-immobilization of enzymes covalently onto functionalized silica microbeads and allows binding a huge amount of HRP and GOX enzymes on the microbeads surfaces which increases the interaction area between immobilized enzymes and the analyte. This has a positive effect on the amount and rate of chemical reactions taking place inside the chamber. The sensor was tested under continuous glucose flow conditions and was found to be able to detect glucose concentrations up to 10 mM with R2 of 0.98 and a limit of detection of 0.7 mM. Such results are very promising for the application in photonic LOC systems used for online analysis.

Highlights

The rapid development in microsystems technology, and its suitability for realizing microfluidics devices, has led to the opening of novel aspects in biomedical and life science applications.miniaturization towards lab-on-a-chip has devoted great interest on many researchers.As a result, many miniaturized devices including: pumps, dispensers, biosensors have been presented recently [1,2].Among these devices, micro biosensors have significant and important impact on the development of lab-on-a-chip systems since they are optimal candidates for detecting cells, antibodies, DNA, and different substrates such as glucose, ethanol and hydrogen peroxide [3].The basic principle of biosensor depends on the interaction of analyte in sample with the biological element
The two fibre optics are first inserted into the PDMS self-alignment fibre optic channels (Figure 2), where one of them is connected to the light source while the other one is connected to the spectrometer
The simple adsorption method was tested after direct immobilization of enzymes on the PDMS

Summary

Introduction

The rapid development in microsystems technology, and its suitability for realizing microfluidics devices, has led to the opening of novel aspects in biomedical and life science applications.miniaturization towards lab-on-a-chip has devoted great interest on many researchers.As a result, many miniaturized devices including: pumps, dispensers, biosensors have been presented recently [1,2].Among these devices, micro biosensors have significant and important impact on the development of lab-on-a-chip systems since they are optimal candidates for detecting cells, antibodies, DNA, and different substrates such as glucose, ethanol and hydrogen peroxide [3].The basic principle of biosensor depends on the interaction of analyte in sample with the biological element (it can be whole cell or part of it, such as enzymes, antibodies or nucleic acids). Many miniaturized devices including: pumps, dispensers, biosensors have been presented recently [1,2]. Among these devices, micro biosensors have significant and important impact on the development of lab-on-a-chip systems since they are optimal candidates for detecting cells, antibodies, DNA, and different substrates such as glucose, ethanol and hydrogen peroxide [3]. The basic principle of biosensor depends on the interaction of analyte in sample with the biological element (it can be whole cell or part of it, such as enzymes, antibodies or nucleic acids) This biological element is attached basically to an interface like the membrane, at which a specific reaction between the biological element and the analyte takes place. As a consequence of this reaction, a specific signal is developed and transformed through the transducer into another signal, which can be more measured and analysed through the detector

Methods

Results

Conclusion